Coriolis Flow Sensor Assembly

ABSTRACT

Provided is a Coriolis flow sensor assembly that includes a fluid flow assembly, including a flow tube, wherein the fluid flow assembly is configured to provide a flow path through the flow tube. The flow tube has at least one region of increased stiffness, which may be a result of a structural support component coupled to the flow tube. In another embodiment, the increased stiffness is caused by integral properties of the flow tube.

BACKGROUND

The present disclosure relates generally to Coriolis flow sensors. Morespecifically, the present disclosure relates to a Coriolis flow sensorassembly with structural modifications that improve sensitivity of themeasurements performed by the Coriolis flow sensor.

Accurate measurements of the properties of fluids delivered through flowsystems is important for a variety of applications, such as inbioprocessing systems and oil and gas pipelines. One technique formeasuring the properties of fluids is by using the flow rate. Thispermits measurements to be performed during fluid delivery, which isadvantageous for reducing associated operating costs. That is, activeflow systems may be operational during measurement. Flow rates may bemeasured either as volumetric flow rates or mass flow rates. Volumetricflow rates are accurate if the density of the fluid is constant;however, this is not always the case as the density may changesignificantly with temperature, pressure, or composition. As such, massflow rates are typically more reliable for measuring fluid flow. Onemethod for measuring mass flow rates is through a Coriolis flow sensor(e.g., a flow meter). In general, a Coriolis flow sensor measures massflow rates via the Coriolis force that results from the fluid as itmoves through an oscillating tube.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimedsubject matter are summarized below. These embodiments are not intendedto limit the scope of the claimed subject matter, but rather theseembodiments are intended only to provide a brief summary of possibleembodiments. Indeed, the disclosure may encompass a variety of formsthat may be similar to or different from the embodiments set forthbelow.

Provided herein is an assembly including a structural support componentconfigured to receive a flow tube, the flow tube being configured toprovide a flow path for a fluid. Further, the assembly includes amechanical drive assembly configured to drive an oscillation of the flowtube and the structural support component while fluid is flowing throughthe flow path, and wherein oscillation of the flow tube in at least oneplane is decreased when the flow tube is coupled to the structuralsupport component.

Provided here in is an assembly including a flow tube configured toprovide a flow path through the flow tube, wherein the flow tube has afirst region and a second region, the first region and the second regionboth having a greater stiffness than a third region. Further, theassembly includes a mechanical drive assembly configured to drive anoscillation of the flow tube while fluid is flowing through the flowpath.

Provided herein is a system including a fluid flow assembly, the fluidflow assembly comprising a flow tube, wherein the fluid flow assembly isconfigured to provide a flow path through the flow tube, wherein theflow tube is formed from a material having a first stiffness at a firstlocation and a second stiffness at a second location, the firststiffness being different than the second stiffness. Further, the systemincludes a mechanical drive assembly configured to drive an oscillationof the flow tube while fluid is flowing through the flow path. Evenfurther, the system includes a sensor configured to sense theoscillation of the flow tube and generate a signal indicative of theoscillation.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of a Coriolis flow sensor system in accordancewith the present disclosure;

FIG. 2 is schematic diagram of oscillations of Coriolis flow sensorassemblies in operation in accordance with the present disclosure;

FIG. 3 shows the Coriolis phase shift of a flow tube having a uniformstiffness;

FIG. 4 shows a comparison of phase shifts of flow tubes of a havinguniform stiffness or a variable stiffness in accordance with the presentdisclosure;

FIG. 5 shows phase shifts of Coriolis flow sensor assemblies having flowtubes with uniform or variable stiffness in accordance with the presentdisclosure;

FIG. 6 is an illustration of implementations of a flow tube of aCoriolis flow sensor assembly having variable stiffness in accordancewith the present disclosure;

FIG. 7 is a schematic illustration of lateral and vertical oscillationof a flow tube of a Coriolis flow sensor assembly in accordance with thepresent disclosure;

FIG. 8 shows phase shifts of a structural support component having adorsal fin in accordance with the present disclosure;

FIG. 9 shows the lateral and drive oscillation mode of a structuralsupport component having a dorsal fin in accordance with the presentdisclosure;

FIG. 10 shows various modes of oscillation of a flow tube of a Coriolisflow sensor in accordance with the present disclosure;

FIG. 11 shows the Coriolis phase shift sensitivity of a flow tubecoupled to a structural support component having lateral and verticalfins in accordance with the present disclosure;

FIG. 12 shows the Coriolis phase shift sensitivity of a flow tube with astructural support component having dual fins in accordance with thepresent disclosure; and

FIG. 13 is an illustration of a structural support feature in accordancewith the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

Coriolis flow sensors are useful in numerous applications that involvefluid delivery, such as bioprocessing systems. In general, a Coriolisflow sensor operates by measuring a phase shift of one or moreoscillating flow tubes that results from a Coriolis force. It isbeneficial to provide a Coriolis flow sensor designs that increases theeffect of the Coriolis force, which in turn results in an increased massflow sensitivity and sensing amplitude (high signal to noise ratio:SNR). Certain Coriolis flow sensors are often used in conjunction with acontinuous tubing that is uniform along its length.

Certain approaches to implementing Coriolis flow sensors aim to magnifythe flow sensitivity by shaping the tubing, and the corresponding fluidflow path, into favorable geometrical forms. However, in addition toimproving the sensitivity of the Coriolis flow sensor measurement, theCoriolis flow sensor should also be robust against environmentaldisturbances that may impact the accuracy of sensor readings. Manyapproaches to modifying the geometric form of the tubing often result inlarge tubing loops that have no advantage in zero point stabilitybecause external disturbances are also magnified (which in turn decreasesensor accuracy). Thus, the effective signal to noise ratio may remainthe same. Further, these configurations also take up additional space ina fluid flow system, and looped geometric form modifies the fluid flowpath; which influence pressure loss, flow velocity, shear rate,trappings, draining, and abrasion.

The present disclosure is directed to a Coriolis flow sensor assemblywith an improved signal to noise ratio. The assembly may include a flowtube (e.g., a disposable flow tube) with features that reduce loss ofoscillation forces. In an embodiment, the Coriolis flow sensor assemblymay include a flow tube with variable stiffness along its length. Asdiscussed in detail below, variable stiffness along the flow tubeimproves the performance of the Coriolis flow sensor assembly byincreasing the Coriolis phase shift of the oscillating tube and byreducing contributions from other oscillation modes (e.g., structuraloscillation modes) to the oscillation imparted by the mechanical driveassembly. In certain embodiments, the variable stiffness along the flowtube results from modifications of the flow tube (e.g., varying theinner wall thickness or varying the material of the flow tube alone itslength). In other embodiments, the variable stiffness along the flowtubes is a result of external structural support components that impartstiffness to certain axes that include oscillation modes that tend tocontribute to sensor noise. Further, the incorporation of the variablestiffness features permits the Coriolis flow sensor assembly to be usedwithout looped or other geometric flow tube structures. For example, thedisclosed techniques may be applied to a Coriolis flow sensor assemblywith a straight or unlooped flow tube, to reduce or eliminate certaindisadvantages associated with conventional looped sensor flow tubes(e.g., taking up space, effects of modifying the fluid flow path). Thatis, the signal to noise ratio improvements achieved via the disclosedtechniques are achieved with a straight or unlooped flow tube. However,it should be understood that the disclosed techniques may also be usedin conjunction with flow tubes with looped or other geometric shapes toaugment signal to noise ratio improvements in such assemblies.

Turning now to the figures, FIG. 1 is a diagram illustrating anembodiment of the Coriolis flow sensor system 10. The Coriolis flowsensor system 10 includes electronics circuitry 12 coupled to a sensorassembly 14. The sensor assembly 14 may include a flow tube and one ormore features that provide increased stiffness to the flow tube.

In one embodiment, the sensor assembly 14 includes a fluid flow assembly18 that provides variable stiffness along a flow tube forming a fluidflow path. For example, the sensor assembly may include a variablestiffness flow tube 20 for retaining a fluid 22. In another embodiment,the variable stiffness flow tube 20 may be coupled to a structuralsupport component 24 that provides and/or augments the variablestiffness by constraining the movement of the flow tube 20 in certainaxes. In certain embodiments, the variable stiffness may be achieved viafeatures integral to the flow tube 20 itself, and the flow tube 20 maybe used in conjunction with the system 10 with or without the structuralsupport component 24. In other embodiments provided herein, thestructural support component may be used in conjunction with a uniformstiffness flow tube (i.e., a flow tube not including the variablestiffness features disclosed herein or a flow tube having a generallyconstant stiffness along its length, such as the flow tube 17 as shownin FIG. 2)

Additionally, the sensor assembly 14 may, in certain embodiments,include one or more sensors 26 and one or more actuators 16. It would beappreciated by those skilled in the art that one or more components ofthe sensor assembly 14 may be configured as disposable parts, and thatother components may be configured as re-usable resident parts. To thatend, in implementations in which certain components are disposable, thedisposable components may be separable (e.g., by an operator usingappropriate tools or by hand) from the resident parts. For example, atleast one of the flow tubes 20, the one or more actuators 16, or the oneor more sensors 26 may be disposable parts, and other parts areconfigured as reusable resident parts. It would be appreciated by thoseskilled in the art that the disposable part(s) may be replaced at verylow cost in intervals governed by the specific process needs. Inaddition, in some implementations, the flow tube 20 may be changed),without the need for replacement of the entire Coriolis flow sensor. Thedisposable-part sub-system allows obtaining high accuracy measurements,reusing of part of the Coriolis flow sensor system 10, provides aflexibility for single-use applications, and achieves cost and materialsavings.

Referring to FIG. 1, in some embodiments, the flow tube 20 may becoupled with a mechanical oscillator 28 or form an assembly with themechanical oscillator 28 and, thus, take the form of a rigid,oscillating tubing during operation of the mechanical oscillator 28. Theone or more actuators 16 are used to induce oscillations of anappropriate amplitude over a required frequency range in the fluid 22through the mechanical oscillator 28 and the flow tube 20. Themechanical oscillator 28 and the actuator 16 are referred tocollectively as the mechanical drive assembly 30. The one or moresensors 26 are configured to provide signals indicative of a Coriolisresponse caused by the fluid 22 flowing through the flow tube 20. Theone or more sensors 26 may include, for example, electromagneticsensors, or optical sensors, and associated components.

The flow tube 20 may be configured as a conduit with an internal passagethat permits fluid flow and may be formed in a shape including, but notlimited to single, dual or multi loop configurations, split flow,straight tube, counter- or co-flow configurations. In someimplementations, the flow tube 20 is made from, for example, a polymerwhose influence on the oscillation modes (harmonic frequencies) of themechanical oscillator is not dominant. In some other examples, the flowtube 20 is made of metal. In yet other examples, the flow tube 20 ismade of glass. The flow tube material, in some examples, is tailored tospecific requirements of the bioprocessing application, such astemperature, pressure, and the characteristics of the fluid to bemeasured (e.g., corrosivity). Further, the flow tube 20 may beimplemented with wall thickness or material features to promote thevariable stiffness along its length as provided herein. The flow tube 20may be arranged to permit in-line fluid flow sensing for a fluidprocessing system. Accordingly, the flow tube may be in fluidcommunication with fluid conduits of a larger fluid processing system.

The Coriolis flow sensor system 10 also includes electronics circuitry12 coupled to the sensor assembly 14. The electronics circuitry 12includes drive circuitry 32 to trigger the one or more actuator(s) 16 togenerate oscillations in the flow tube 20 of the desired frequency andmagnitude. The Coriolis flow sensor system 10 further includes sensorcircuitry 34 to receive the Coriolis response from the flow tube 20. Theelectronics circuitry 12 further includes a processor 36 to process theCoriolis response signals received from the sensors 26 to generate oneor more measurements representative of one or more properties of thefluid. These measurements are displayed via a user interface 38. Theelectronics circuitry 12 also includes a memory 40 to store themeasurements for further use and communication, to store data useful forthe drive circuitry 32, and the sensor circuitry 34.

In operation, the electronics circuitry 12 triggers the one or moreactuator(s) to generate oscillations in the flow tube 20, which aretransferred to the fluid 22. Due to these oscillations, the Coriolisresponse (vibration amplitude and phase) is generated in the fluid andis sensed by the sensors 26 through the flow tube 20. The sensedCoriolis response signal from the sensors 26 are transmitted to theelectronics circuitry 12 for further processing to obtain themeasurements of the one or more properties of the fluid including fluidflow.

The system 10 may be used to assess fluid characteristics in any fluidflow system. As disclosed, the fluid characteristics may be assessedduring operation of a variety of manufacturing and/or fluid flowprocesses. Some applications for the system 10 described herein includefabrication of wafers in semi-conductor industry, and medicalapplications that involve use of organic fluids. Some of these are highpurity applications, and use of flow tube 20 made of for examplepolymer, or other chemically inert material is advantageous in suchapplications. In some other applications, a flow tube 20 formed ofelectrically inert and low thermal conductivity material like glass isadvantageous.

FIG. 2 illustrates oscillation diagrams 42, 44, and 46 of exampleoscillation modes. The oscillation diagram 42 shows a uniform stiffnessflow tube 17 relative to oscillation diagrams 44 and 46, which showfluid flow assemblies 18 with flow tubes 20 having variable stiffnessthat may be used in conjunction with the Coriolis flow sensor system 10as provided herein. As shown, each flow tube 20 may be coupled to amechanical oscillator 28 that drives the oscillation of each flow tube20. The system 10 may include two sensors 28 that sense the oscillation.

The flow tubes 20 shown in oscillation diagrams 44 and 46 include one ormore regions 23 of increased stiffness positioned along to the flow tube20. The regions of increased stiffness are relative to regions 25 thatare less stiff. In certain embodiments, the increased stiffness mayresult from one or more of the flow tube 20 being formed from differentmaterials in the one or more regions 23 relative to the regions 25 thatare less stif, increased wall thickness of the flow tube 20 in theregions 23 relative to wall thickness of the flow tube 20 in the lessstiff regions 25, or via one or more structural support components 24(e.g., as shown in FIG. 7) coupled to the flow tube.

In operation, a force 48 is applied to approximately the center 31 ofthe flow tube 20, as measured along the length or fluid flow axis (e.g.,as shown by the flow arrow 52) and which may correspond to half thedistance between a fluid entry point 27 and a fluid exit point 29 of theflow tube 20, by the mechanical oscillator 28 of the mechanical driveassembly 30. The force 48 results in a typical drive deflection shape50. Upon a flow 52 (e.g., of fluid 22, shown flowing in the direction ofthe arrow 52), a Coriolis force distribution 54 is exerted on the flowtube 20, resulting in a rotation 56 of the flow tube. The combination ofthe Coriolis force distribution 52 and the drive deflection shape 50 isa Coriolis deflection shape 58.

The Coriolis deflection shape, w, depends on the Coriolis forcedistribution 52 and the bending stiffness of the flow tube. A Coriolisphase shift, Δt, is determined by a relationship between the drivedeflection shape 48, ν, of the flow tube and Coriolis deflection shape58, w at a specific frequency, f:

${\Delta t} = {{- \frac{1}{f}}{\tan^{- 1}\left( \frac{w}{v} \right)}}$

As discussed above, Coriolis phase shift is used to measure propertiesof the fluid and the rate of fluid flow. In general, a greater Coriolisphase shift results in a higher sensitivity of measurement. The Coriolisphase shift can be determined with the relationship of drivedisplacement to Coriolis displacement.

A variable bending stiffness along the oscillator axis (e.g., in thedirection of the force 48) influences at both the drive deflection shape48 and the Coriolis force distribution, resulting in a modified Coriolisdeflection shape. Moreover, the variable bending stiffness shifts theCoriolis force distribution along oscillator axis, which shifts theCoriolis force distribution 54 towards oscillation maximum. Oscillationdiagrams 44 and 46 illustrate how the Coriolis deflection shape 52changes with variable stiffness distributions imparted by the regions 23of increased stiffness. Schematic 44 illustrates that increasedstiffness at the ends of the oscillator axis (i.e., at the fluid entrypoint 27 and the fluid exit point 29), shifts the Coriolis forcedistribution 64 maximum towards the center of the oscillator. Hence, theCoriolis force cause a higher Coriolis movement in the sensed area,which results in an increased phase shift. As shown in schematic 48,when the region or regions 23 of increased stiffness are positioned atthe center 31 of the flow tube, the drive deflection shape 48 may beflattened at the center. Thus, the Coriolis force distribution 52 andCoriolis deflection shape are defocused and shifted towards the rotationaxis, resulting in less Coriolis phase shift relative to homogeneousbending stiffness or increased bending stiffness near to the rotationaxis. Accordingly, in certain embodiments, the flow tube 20 is providedwith one or more regions 23 of increased stiffness that are positionedadjacent to the fluid entry point 27 and/or the fluid exit point 29 ofthe flow tube 20. Further, the flow tube 20 may have one or more regions23 of increased stiffness that are positioned to avoid or exclude themidpoint 31 of the flow tube 20 (e.g., the midpoint between the fluidentry point 27 and the fluid exit point 29). The flow tube 20 may haveone, two, or any number of regions 23 of increased stiffness.

FIG. 3 shows experimental results for assessing Coriolis phase shift inconjunction with a uniform stiffness flow tube 17 with a constantstiffness and a corresponding graph 70 of the Coriolis phase shiftsensitivity. An image 72 shows the experimental setup for determiningthe Coriolis phase shift sensitivity (e.g., Coriolis phase shift basedon flow rate) with the flow tube coupled to a mechanical drive assembly30. The graph 70 displays the Coriolis phase shift versus the scale flowrate (kg/min). Points 74 represent repeated measurements of the Coriolisflow sensor having flow tube 20 illustrated in image 72. For thisconfiguration, the measured Coriolis phase shift ranges fromapproximately 2 to 10 μs from a flow rate up to 10 kg/min. The measuredCoriolis phase shift of flow tube shown in image 72 is 4 μs based on a4.7 kg/min flow and a 150 Hz drive oscillation.

FIG. 4 is a schematic illustration comparing phase shifts between auniform stiffness flow tube 17 and a variable stiffness flow tube 20having the variable stiffness (e.g., along the axis 78), in accordancewith the present disclosure. Flow tube 17 has a continuous stiffnessdistribution and has a phase shift of 4 μs based on a 4.7 kg/min flowand a 150 Hz drive oscillation, calculated using Finite Element Analysis(FEA). The phase shift of flow tube 20 is 37 μs based on a 4.7 kg/minflow and a 150 Hz drive oscillation is, calculated using FEA.

FIG. 5 shows the uniform stiffness flow tube 17 relative to variousimplementations of the variable stiffness flow tube 20 (illustrated asflow tubes 82, 84, 86, and 88) with a variable bending stiffnessdistributions with corresponding Coriolis phase shift sensitivities thatcalculated using Finite Element Analysis (FEA). Each flow tube 17, 20has a variable bending stiffness across the length 90 (e.g., flow axis91). The magnitude of the bending stiffness of each flow tube 17, 20 isrelated to the height 92 along the axis 94 (e.g., vertical axis). Forexample, flow tube 82 has two regions of greater bending stiffnesswithin approximately the first 25% and last 25% of the length of eachflow tube. Flow tubes 84, 86, and 88 show variable (e.g., graded)stiffness along the length of each flow tube.

The phase difference, Δt, of each flow tube 17, 20 (82, 84, 86, and 88)was calculated using Finite Element Analysis (FEA) simulations based ona constant flow of 4.7 kg/min and a flow tube inner diameter (ID) of 6.3mm. The lengths of each arrow 96 (several are annotated in FIG. 4)represents the magnitude of the Coriolis force on the flow tubes 17, 20(82, 84, 86, and 88). The calculated phase difference of flow tubes 17,20 (82, 84, 86, and 88) is 4.5, 8.1, 14.3, 12.4, 4.4, 2.9 μs,respectively. Each calculated phase difference is measured at the sameposition for each flow tube. The flow tube 82 had the highest phasedifference of the flow tubes represented herein (e.g., a phasedifference of 14.3 μs), which indicates it has the highest sensitivity.Thus, FIG. 5 shows that there is a distribution of stiffness across theflow tube 20 that results in the greatest performance (e.g., high flowsensitivity). While the flow tubes 17, 20 (82, 84, 86, and 88) shown inFIG. 5 are all generally straight about the flow axis, it should beappreciated by one of ordinary skill in the art that the effect ofimproved performance with a modified stiffness of the flow tubes 20extends to flow tubes of other geometries as provided herein.Accordingly, as provided herein, the flow tube 20 may be formed having alower (e.g., minimum) stiffness region 25 that extends across themidpoint 31 and that is flanked by relatively higher or increasedstiffness regions 23. The increased stiffness regions 23 of the flowtube 20 may have stepped or nonconstant thickness such that individuallocations within the increased stiffness region or regions 23 haveincreased stiffness relative to the lower stiffness region 25 but mayhave different stiffness relative to other locations in the increasedstiffness region or regions 23. It should also be understood that otherimplementations are contemplated. For example, the flanking increasedstiffness regions 23 a and 23 b may have the same stiffness as oneanother or may have different stiffness relative to one another whilebeing nonetheless higher in stiffness than the lower stiffness region25. Further, the increased stiffness regions 23 a and 23 b may be thesame length or different lengths. In addition, the increased stiffnessregion 23 a or 23 b may be eliminated in certain implementations. In oneembodiment, the increased stiffness region 23 (e.g., 23 a and/or 23 b)may be about 5-30% of a total length of the flow tube 20, as measuredfrom the fluid entry point 27 to the fluid exit point 29. The loweststiffness region 25 may be about 20-80% (e.g., 20-30%, 20-40%, 20-50%,30-60%) of a total length of the flow tube 20, as measured from thefluid entry point 27 to the fluid exit point 29. In addition, the loweststiffness region 25 may be symmetrical about the midpoint 31 or may beasymmetric with respect to the midpoint 31. Regardless of the specificconfiguration, the flow tube 20 may be configured such that a firstlocation on the flow tube has a different stiffness (e.g., determinedfrom geometry, harmonic motion, or Young's modulus) than a secondlocation spaced apart from the first location along the fluid flow path.

FIG. 6 shows cross-sectional views of several exemplary implementationsfor a variable stiffness flow tube 20 with variable stiffness along thelength of the flow tube 20 for use in conjunction with the Coriolis flowsensor system 10 as provided herein. Flow tube 100 has a graduallyvarying wall thickness 102 along the length 90 that imparts theincreased stiffness. While flow tube 100 illustrates a linear variationin thickness 102, any grade change of thickness is permissible. Ingeneral, the flow tube has a greater thickness at locations 104 and 108relative to location 106. Flow tube 109 has increased stiffness at theends 110 resulting from periodically-spaced increased thickness regions112, e.g., ribs of increased thickness that are distributed at locationsto promote higher signal to noise ratios. Flow tube 114 illustratesvariable stiffness achieved through variable material composition of theflow tube. For example, the center of the flow tube is made of a firstmaterial 116 which is flanked by material 118 and material 120.Materials 118 and 120 may be the same or different materials. Therelative stiffness of materials 116, 118, and 120 may differ withregards to the desired variable stiffness. For example, materials 118and 120 may be stiffer than material 116 to achieve an increasedstiffness on the ends. Such variation in thickness or materials may beachieved using appropriate extrusion parameters when manufacturing theflow tube 20. Further, the variable stiffness of the flow tube 20 may beachieved by providing additives or stiffeners (e.g., additive particles,wire) to the material of the flow tube 20 in the increased stiffnessregion(s) 23 and not in the lower stiffness region 25. In certainembodiments, any change in thickness or material composition may beabout the entire circumference of the flow tube 20, while in otherembodiments the change in thickness or material composition may beapplied to only part of the circumference of the flow tube in anincreased thickness region or location.

As discussed generally herein, varying the stiffness in the direction ofthe oscillation axis along the flow axis (e.g., axis 91) of the flowtubes modifies the oscillations (e.g., modes) along the oscillation axis(e.g., vertical axis 94). Additionally, there are other factors fortuning the oscillation that result in an increased Coriolis phase shift.FIG. 7 is a schematic illustration of a vertical axis 122 and a lateralaxis 124 along a flow tube 20. As shown, the oscillation 126 occurs in aplane 125 spanning the vertical axis 122 and the flow axis 91. Unwantedharmonic modes (e.g., structural modes) may occur along the axes 122 and124 and contribute to the Coriolis deflection shape (e.g., Coriolisdeflection shape 58; FIG. 2). In order to damp or shift the frequency ofunwanted harmonic modes of tubing fluid flow assembly 18, additionalstructural features may be added to either a uniform stiffness flow tube17, as shown, or a variable stiffness flow tube 20 (e.g., modalfeatures). Structural features along certain axes (e.g., 122 and 124)may provide independent influence on the different vibration modes witha variable cross section that adjusts (e.g., shift the frequency of theharmonic mode up, shift the frequency down, or decrease the amplitude)the unwanted harmonic modes until the effect of the unwanted harmonicmodes is negligibly, resulting in increased sensitivity and robustnessof the Coriolis flow sensor assembly. The features that alter theunwanted harmonic modes (e.g., modal features) may have various designs,structures, and properties to address different modes.

For example, modal features may include vertical fin structures 127 toincrease stiffness in the vertical axis 122, resulting in better controlof the Coriolis deflection shape. Additionally, modal features mayinclude lateral fin structures 128 (e.g., pectoral fins) to adjust(e.g., prevent, shift, or decrease) modes along the lateral axes 124.The lateral fin structures 128 increase the stiffness in the lateralplane while providing little to no negative effects on the modes alongthe vertical axis 122. In one embodiment, the vertical fin structure 127may be formed integrally with the structure of the flow tube 20 via anextension or a variable thickness of the walls of the flow tube. Incertain embodiments, the vertical fin structure or other structures asprovided herein may be implemented as a structural support component 24that is coupled to the flow tube 20. In one embodiment, the structuralsupport component 24 is reversibly coupled to the flow tube 17 or theflow tube 20 to permit exchanging or replacing used flow tubes whileretaining the reusable components of the sensor assembly 14 (FIG. 1). Itshould be appreciated by one of ordinary skill in the art that thestructural support component 24 addition to modify the stiffness of theflow tube as discussed in FIG. 5. Moreover, one of ordinary skill in theart would recognize that an attachable structural support component maybe suitable for a disposable (e.g., attachable and removable) orreusable flow tube. When coupled to the flow tube (e.g., flow tube 17 orflow tube 20), the structural support component 24 is configured topermit oscillation of the coupled flow tube. In certain embodiments, thestructural support component oscillates together with the flow tube.

FIGS. 8 and 11-13 illustrate different embodiments of a Coriolis flowsensor. In particular, FIGS. 8 and 11-13 show a flow tube coupled to astructural support component 24 having different features (e.g., fins)and an associated Coriolis phase shift sensitivity measurement. Ingeneral, the embodiments discussed below show increased Coriolis phaseshift sensitivity, which is exemplified by the range of measuredCoriolis phase shifts based on flow rates.

FIG. 8 shows a vertical fin structural support component 24 coupled tothe flow tube in accordance with the present disclosure. Image 128 showsthe experimental setup used to determine the Coriolis phase shiftsensitivity based on variable flow rates. The image 128 shows the flowtube, the oscillator 28, and the vertical fin structural supportcomponent 24. The graph 130 shows the Coriolis phase shift versus theflow rate of the flow tube in image 128. The points 132 from themeasured Coriolis phase shift versus flow rate generally fit a line.

FIG. 9 shows the lateral mode 136 and drive or operating mode 138 of animplementation of the structural support component 24. The FEAsimulation shows the lateral mode has a frequency of 97 Hz, which isclose to the operating mode frequency of 150 Hz. It should beappreciated by one of ordinary skill in the art that while the Coriolisflow sensor assembly performed well (e.g., the measured phase shifts fora given flow rate fit a linear equation) additional modifications (e.g.,modal features) may improve the performance of the Coriolis flow sensorassembly for certain conditions (e.g., flow rates). The illustratedstructural support component 24 may have a body 125 that includesextending fin portion(s) 127 that are generally positioned at areas thatcorrespond with the flow tube ends (e.g., the fluid entry point 27 andexit point 29) and that extend away from the flow tube a distance d₁.The body is thinner in a center portion 135, e.g., extending to adistance d₂ that is less than d₁. To couple to the flow tube, the body125 includes a plurality of ribs 137 that form a receiving area 139 andthat are sized and shaped to couple to the flow tube (e.g., flow tube 17or flow tube 20), for example by forming a partial annulus about theflow tube that permits an operator to insert and/or remove the flowtube. A flow tube, when coupled to the structural support component 24,would experience decreased oscillation along a lateral plane extendingoutwardly from the lateral mode arrows 136.

FIG. 10 shows a plot of the frequencies of the drive oscillation, 140,the lateral mode 142, and the bending mode 144. An illustration of themodes is shown in 141, 143, and 145 for each mode 140, 142, and 144respectively. The structural support components adjust the harmonic mode(e.g., shift the frequency of the mode up or down or decrease theamplitude until the unwanted modes can be neglected). For example, afrequency margin of at least 1.5 between the drive oscillation and thelateral mode was found to significantly decrease the dynamic response ofthe lateral mode. Additionally, a frequency margin of at least 2.0between the drive oscillation and the bending mode resulted inadditional improvements of the performance of the Coriolis flow sensorassembly.

FIG. 11 shows the Coriolis phase shift sensitivity of a Coriolis flowsensor assembly including the flow tube 20 coupled to an implementationof the structural support component 24 having vertical fins and lateralfins in accordance with the present disclosure. Image 148 shows anexperimental setup used to determine Coriolis phase shift sensitivitybased on variable flow rates that includes the flow tube 20, theoscillator 30, and the structural support component 146. As shown in theschematic 150, the flow tube oscillates in a direction 152 that isperpendicular to the flow path. The graph 154 shows the Coriolis phaseshift versus the flow rate of the flow tube depicted in image 146 havingthe structural support component 24 illustrated in schematic 150. Themeasured Coriolis phase shift versus flow rate for the flow tube 20coupled to the structural support component 24 fits linear equation(e.g., represented as line 156). The measured Coriolis phase shift of aCoriolis flow sensor assembly including the structural support component24 having vertical fins and laterals fins is 19 μs, which is greaterthan the 4 μs phase shift of a Coriolis flow sensor assembly havingconstant stiffness.

FIG. 12 shows the Coriolis phase shift sensitivity for a flow tube 20coupled to an implementation of a dual fin structural support component24 in accordance with the present disclosure. Image 160 shows anexperimental setup used to determine the Coriolis phase shiftsensitivity based on variable flow rates including the flow tube 20, theoscillator 30, and the dual fin structural support component 24. Thedual fin structural support component 24 includes an interior space 158between the fin structures. As illustrated, the interior space 158 ishollow; however, in other embodiments, the interior space 158 may besolid, or partially solid (e.g., porous), and may be composed of amaterial that is different than the rest of the dual fin structuralsupport component 24. A first schematic 162 shows an illustration of thedual fin structural support component 24 with Coriolis forcesillustrated as arrows 164. A second schematic 166 shows a sideperspective view of the dual fin structural support component 24. Thegraph 168 shows the Coriolis phase shift versus the flow rate of theflow tube depicted in schematics 162, 166, and image 160. The measuredCoriolis phase shift of a Coriolis flow sensor assembly including thedual fin structural support component 24 is 22 μs, which is greater thanthe 4 μs phase shift of a Coriolis flow sensor assembly having constantstiffness.

FIG. 13 shows a structural support feature 24 in accordance with thepresent disclosure. As discussed above, structural support features maybe added to the Coriolis flow tube to reduce the effects of unwantedharmonic oscillations on the drive oscillation that results from themechanical drive assembly 32. In general, structural support componentsmay have features that address unwanted harmonic oscillations in oneaxis (e.g., either vertical or lateral). For example, although thestructural support component having vertical fins shown in FIG. 8improved the Coriolis phase shift sensitivity of the Coriolis flowsensor assembly, the Coriolis flow sensor assembly showed a lowersensitivity under certain conditions (e.g., at point 110). Thestructural support component 116 with lateral and vertical fins, shownin FIG. 10, results in increased Coriolis phase shift sensitivity;however, in certain embodiments, it would be recognized by one ofordinary skill in the art that additional features (e.g., modalfeatures) may add less desirable bulkiness of the flow tube. FIG. 13illustrates a structural support component 24 with features that addressunwanted harmonic features along several axes. In general, thestructural support component 24 permits different regions of the flowtube to have variable bending stiffness, lateral stiffness, and verticalstiffness. When coupled to the flow tube, the structural supportcomponent 24 may be in direct contact with the flow tube along anentirety of the length of the flow tube or, in certain embodiments,along some of a length of the flow tube.

The structural support component 24 illustrated in FIG. 13 has a firstregion 172, a second region 174, and a third region 176 along a backbone structure 178 having rib structures 180 that allow for thestructural support component 24 to couple to the flow tube 20. Thebackbone structure 178 has a first backbone 182 and a second backbone184 separated by a distance 186. The first region 172 and the secondregion 174 have similar structural features. Moreover, the distance 186between the first backbone 182 and the second backbone 184 is similar.Image 188 illustrates a representative cross sectional view along thelength of the structural support component 24 in the third region 176.Image 190 illustrates a representative cross sectional view along thelength of the structural support component 24 in the first region 172and the second region 174. As shown, the distance 186 between the firstbackbone 182 and the second backbone 184 (e.g., a greater arc lengtharound the rib structure 180) in the first region 172 and second region174 is greater than the distance 186 between the first backbone 182 andthe second backbone 184 shown in image 190. A greater distance 186results in greater lateral stiffness. Thus, the lateral stiffness alongthe flow tube 20 may be tuned based on the distance between thebackbones 182 and 184.

As further illustrated in FIG. 13, the first backbone 182 and secondbackbone 184 have a variable thickness. In the first region 172 and thesecond region 174, the backbone has a greater thickness 192 than in thethird region. The greater backbone thickness 192 results in a greatervertical stiffness of the flow tube 20 when the structural supportcomponent 170 is coupled to the flow tube 20. The thinner backbonethickness 192 of the third region 176 imparts a lower vertical stiffnessto the flow tube 20 when the structural support component is coupled tothe flow tube 20. Thus, the structural support component 170 may imparta variable vertical stiffness to the flow tube 20 in additional to avariable lateral stiffness.

The disclosure relates to a Coriolis flow sensor with features thatreduce the contributions of unwanted harmonic modes to the oscillationresulting from the mechanical drive assembly. As discussed herein, thefeatures may include a flow tube with variable stiffness, which may beimplemented through features of the flow tube itself such as a variablewall thickness of the flow tube or through varying the materialcomposition of the flow tube. Additionally, variable stiffness may beachieved by including structural support features integrally with or viaan external structural support component coupled to the flow tube. Thestructural support component may include subcomponents (e.g., fins andbackbones) that affect the stiffness of the flow tube along differentaxes that damp or shift the frequency of unwanted oscillations from thefrequency of the oscillation imparted by the oscillator.

This written description uses examples to enable any person skilled inthe art to practice the embodiments of the disclosure, including makingand using any devices or systems and performing any incorporatedmethods. The patentable scope is defined by the claims, and may includeother examples that occur to those skilled in the art. Such otherexamples are intended to be within the scope of the claims if they havestructural elements that do not differ from the literal language of theclaims, or if they include equivalent structural elements withinsubstantial differences from the literal languages of the claims.

1. An assembly comprising: a structural support component configured toreceive a flow tube, the flow tube being configured to provide a flowpath for a fluid; and a mechanical drive assembly configured to drive anoscillation of the flow tube and the structural support component whilefluid is flowing through the flow path, wherein oscillation of the flowtube in at least one plane is decreased when the flow tube is coupled tothe structural support component.
 2. The assembly of claim 1, whereinthe structural support component comprises a body that extends away fromthe flow tube when the flow tube is coupled to the structural supportcomponent, wherein a first portion of the body extends away from theflow tube a first distance and wherein a second portion of the bodyextends away from the flow tube a second distance, the first distancebeing greater than the second distance.
 3. The assembly of claim 1,wherein the structural support component forms a partial annulus aboutthe flow tube when coupled to the flow tube.
 4. The assembly of claim 1,wherein the structural support component extends along an entire lengthof the flow tube when coupled to the flow tube such that the flow tubeis in direct contact with at least a portion of the structural supportcomponent along the entire length.
 5. The assembly of claim 1, whereinthe structural support component is different in a first and a secondregion relative to a third region, wherein the third region is flankedby the first region and the second region.
 6. The assembly of claim 1,wherein the flow tube is configured to be reversibly coupled to thestructural support component.
 7. The assembly of claim 1, wherein thestructural support component comprises a plurality of ribs distributedalong its length, wherein the plurality of ribs are configured toreceive the flow tube.
 8. The assembly of claim 1, wherein thestructural support component comprises at least one fin that extends ina lateral direction away from the flow tube.
 9. The assembly of claim 1,wherein the flow tube coupled to the structural support component. 10.The assembly of claim 9, wherein the flow tube comprises a firstlocation having increased stiffness relative to a second location of theflow tube.
 11. An assembly comprising: a flow tube configured to providea flow path through the flow tube, wherein the flow tube has a firstregion and a second region, the first region and the second region bothhaving a greater stiffness than a third region; and a mechanical driveassembly configured to drive an oscillation of the flow tube while fluidis flowing through the flow path.
 12. The assembly of claim 11, whereinthe flow tube is formed from a material having variable wall thicknessand wherein a first wall thickness of the first region and a second wallthickness of the second region are greater than a third wall thicknessof the third region.
 13. The assembly of claim 11, wherein the firstregion or the second region is 25% or less of a total length of the flowtube.
 14. The assembly of claim 11, wherein the third region is longerthan the first region and the second region.
 15. The assembly of claim11, wherein the third region is flanked by the first region and thesecond region.
 16. The assembly of claim 11, wherein the first region,the second region, and the third region are arranged along a flow axisof the flow path.
 17. The assembly of claim 11, wherein the flow tubedefines a generally straight flow path.
 18. The assembly of claim 11,wherein the flow tube is disposable.
 19. The assembly of claim 11,further comprising a structural support component reversibly coupled tothe flow tube, wherein the structural support component couples to theflow tube to result in the greater stiffness of the first region and thesecond region relative to the third region.
 20. The assembly of claim19, wherein said stiffness is a bending stiffness.
 21. A systemcomprising: a fluid flow assembly, the fluid flow assembly comprising aflow tube, wherein the fluid flow assembly is configured to provide aflow path through the flow tube, wherein the flow tube is formed from amaterial having a first stiffness at a first location and a secondstiffness at a second location, the first stiffness being greater thanthe second stiffness; a mechanical drive assembly configured to drive anoscillation of the flow tube while fluid is flowing through the flowpath; and a sensor configured to sense the oscillation of the flow tubeand generate a signal indicative of the oscillation.